From: Alex Hung <alex.h...@amd.com>

[ Upstream commit 031f196d1b1b6d5dfcb0533b431e3ab1750e6189 ]

[WHY]
When PTEBufferSizeInRequests is zero, UBSAN reports the following
warning because dml_log2 returns an unexpected negative value:

  shift exponent 4294966273 is too large for 32-bit type 'int'

[HOW]

In the case PTEBufferSizeInRequests is zero, skip the dml_log2() and
assign the result directly.

Reviewed-by: Jun Lei <jun....@amd.com>
Acked-by: Qingqing Zhuo <qingqing.z...@amd.com>
Signed-off-by: Alex Hung <alex.h...@amd.com>
Tested-by: Daniel Wheeler <daniel.whee...@amd.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 .../gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c   | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c 
b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
index e427f4ffa0807..e5b1002d7f3f0 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
@@ -1868,7 +1868,10 @@ static unsigned int CalculateVMAndRowBytes(
        }
 
        if (SurfaceTiling == dm_sw_linear) {
-               *dpte_row_height = dml_min(128, 1 << (unsigned int) 
dml_floor(dml_log2(PTEBufferSizeInRequests * *PixelPTEReqWidth / Pitch), 1));
+               if (PTEBufferSizeInRequests == 0)
+                       *dpte_row_height = 1;
+               else
+                       *dpte_row_height = dml_min(128, 1 << (unsigned int) 
dml_floor(dml_log2(PTEBufferSizeInRequests * *PixelPTEReqWidth / Pitch), 1));
                *dpte_row_width_ub = (dml_ceil(((double) SwathWidth - 1) / 
*PixelPTEReqWidth, 1) + 1) * *PixelPTEReqWidth;
                *PixelPTEBytesPerRow = *dpte_row_width_ub / *PixelPTEReqWidth * 
*PTERequestSize;
        } else if (ScanDirection != dm_vert) {
-- 
2.39.2

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